Covalent Organic Frameworks (COFs) are a class of porous covalent materials which are frequently synthesized as unprocessable crystalline powders. The first COF was reported in 2005 with much effort ...centered on the establishment of new synthetic routes for its preparation. To date, most available synthetic methods for COF synthesis are based on bulk mixing under solvothermal conditions. Therefore, there is increasing interest in developing systematic protocols for COF synthesis that provide for fine control over reaction conditions and improve COF processability on surfaces, which is essential for their use in practical applications. Herein, we present a novel microfluidic-based method for COF synthesis where the reaction between two constituent building blocks, 1,3,5-benzenetricarbaldehyde (BTCA) and 1,3,5-tris(4-aminophenyl)benzene (TAPB), takes place under controlled diffusion conditions and at room temperature. Using such an approach yields sponge-like, crystalline fibers of a COF material, hereafter called MF-COF. The mechanical properties of MF-COF and the dynamic nature of the approach allow the continuous production of MF-COF fibers and their direct printing onto surfaces. The general method opens new potential applications requiring advanced printing of 2D or 3D COF structures on flexible or rigid surfaces.
Functionalized with porphyrins: The interactions of metalloporphyrins with graphene oxide and pyridine‐substituted graphene oxide have been probed (see figure). The interactions elucidated offer ...unprecedented tools in the quest for functional nanostructured materials.
We report on a fast and simple method to produce highly stable isopropanol/water (4:1) suspensions of few‐layer antimonene by liquid‐phase exfoliation of antimony crystals in a process that is ...assisted by sonication but does not require the addition of any surfactant. This straightforward method generates dispersions of few‐layer antimonene suitable for on‐surface isolation. Analysis by atomic force microscopy, scanning transmission electron microscopy, and electron energy loss spectroscopy confirmed the formation of high‐quality few‐layer antimonene nanosheets with large lateral dimensions. These nanolayers are extremely stable under ambient conditions. Their Raman signals are strongly thickness‐dependent, which was rationalized by means of density functional theory calculations.
Stabile Suspensionen aus hochwertigem, ein‐ oder mehrschichtigem Antimonen wurden durch Flüssigphasenexfoliation unter Ultraschallbehandlung erhalten, ohne dass ein Tensid benötigt wurde. Das Raman‐Spektrum von Antimonen hängt stark von dessen Dicke ab, was durch quantenmechanische Rechnungen bestätigt wurde.
Antimonene, a novel group 15 two‐dimensional material, is functionalized with a tailormade perylene bisimide through strong van der Waals interactions. The functionalization process leads to a ...significant quenching of the perylene fluorescence, and surpasses that observed for either graphene or black phosphorus, thus allowing straightforward characterization of the flakes by scanning Raman microscopy. Furthermore, scanning photoelectron microscopy studies and theoretical calculations reveal a remarkable charge‐transfer behavior, being twice that of black phosphorus. Moreover, the excellent stability under environmental conditions of pristine antimonene has been tackled, thus pointing towards the spontaneous formation of a sub‐nanometric oxide passivation layer. DFT calculations revealed that the noncovalent functionalization of antimonene results in a charge‐transfer band gap of 1.1 eV.
Maßgeschneiderte Flocken: Die nichtkovalente Funktionalisierung von Antimonen mit Perylenbisimid (PDI) wird beschrieben. Die starke Fluoreszenzlöschung von PDI ermöglicht die direkte Charakterisierung der auf Si/SiO2‐Substraten abgeschiedenen Antimonenflocken. Die Ergebnisse bereiten den Weg für neuartige Anwendungen auf Antimonenbasis durch die gezielte Justierung der elektronischen Eigenschaften.
•Experimental characterization of few-layer antimonene electrical properties.•Few-layer antimonene electrical transport seems to be independent of the thickness.•Theory indicates that topologically ...protected surface states are playing a role.
Antimonene -a single layer of antimony atoms- and its few layer forms are among the latest additions to the 2D mono-elemental materials family. Numerous predictions and experimental evidence of its remarkable properties including (opto)electronic, energetic or biomedical, among others, together with its robustness under ambient conditions, have attracted the attention of the scientific community. However, experimental evidence of its electrical properties is still lacking. Here, we characterized the electronic properties of mechanically exfoliated flakes of few-layer (FL) antimonene of different thicknesses (∼ 2–40 nm) through photoemission electron microscopy, kelvin probe force microscopy and transport measurements, which allows us to estimate a sheet resistance of ∼ 1200 Ω sq−1 and a mobility of ∼ 150 cm2V−1s−1 in ambient conditions, independent of the flake thickness. Alternatively, our theoretical calculations indicate that topologically protected surface states (TPSS) should play a key role in the electronic properties of FL antimonene, which supports our experimental findings. We anticipate our work will trigger further experimental studies on TPSS in FL antimonene thanks to its simple structure and significant stability in ambient environments.
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Sonication‐assisted liquid‐phase exfoliation of antimony crystals gives rise to very stable suspensions of high‐quality single/few‐layer antimonene, as shown by G. Abellán, F. Zamora, and co‐workers ...in their Communication on page 14345 ff. A new nanomaterial was thus produced that will facilitate the development of a broad range of applications based on antimonene, including electronics and optoelectronics.
Microgravity has proved to be an ideal condition to grow crystals. In article number 2101777, Raphael Pfattner, Tiago Sotto Mayor, Daniel Ruiz‐Molina, Josep Puigmartí‐Luis, and co‐workers demonstrate ...how to generate simulated microgravity on Earth to grow 2D porous crystalline molecular frameworks such as 2D metal–organic frameworks and 2D covalent organic frameworks.
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